New wet-replication technique. II. Replication of various wet specimens

Abstract

The physical ability of a differentially pumped hydration chamber to replicate water surfaces and droplets has been proven in the preceding report. This has provided a new approach to tackle some questions of solid-state nucleation, aerosol science, and fluid dynamics. In this report, the physical aspects of the wet-replication technique have been described with particular attention to the flow of evaporating gases through saturated water vapor in a hydration chamber. The reasons for selecting SiO as the replicating material when biological specimens are used are explained. At low water-vapor pressure the outward SiO beam is diffracted by the streaming water vapor. At higher vapor pressures the flow pattern changes to an effusive type and cross-beam collision predominates near the axis of the inner aperture. The penetrating central SiO beam is thus involved in random collisions until it is thermalized in the water vapor. Some SiO molecules are dragged or diffused toward the cooler specimen surface to produce a replica of all lateral and reentrant surfaces of the specimen. This shape-replication ability of the present technique has been demonstrated using objects of various sizes in the range 100 Å–10 μm and of different degrees of rigidity. The technique at hand may have some limitations when applied on delicate processes and to soft biological materials, and some modifications of the technique are suggested accordingly.